string rep = "";
rep = constring;
SqlCommand cmd = new SqlCommand(rep, sqlcon);
SqlDataAdapter sqlada = new SqlDataAdapter(cmd);
sqlada.Fill(ds);
datetime是日期类型,看你怎么转换成字符串的展示代码看看
显示日期的代码怎么样的,实在不行ToString格式化下
var s=DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");